Method and apparatus for coordinating a wireless PAN network and a wireless LAN network

ABSTRACT

Devices of a personal area network (PAN) use a wireless medium that is shared with a wireless local area network (WLAN). WLAN devices communicate using protocols of the WLAN and PAN devices communicate using PAN protocols allowing for lower power transmissions over the wireless medium relative to transmissions over the WLAN. A PAN coordinator device obtains access to the wireless medium for the PAN devices by signalling a reservation of the medium by the PAN coordinator device, such that the other devices defer use of the wireless medium, including at least one WLAN device, for a reservation period. During the reservation period, the communication is done using the PAN protocol. The signalling can be implicit in that the PAN coordinator device transmits one or more frame using the PAN protocol but that is at least partially understandable by WLAN devices such that they defer upon receipt of one or more of the PAN protocol frames, which may be a standard or modified HCCA-CF poll frame, a CTS frame with an increased duration field, or other variation. A PAN coordinator might also signal an access point to set up a DLS link between the PAN coordinator and itself and use the DLS period for PAN traffic.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/340,465 filed Dec. 29, 2011 which is a continuation of U.S. patentapplication Ser. No. 11/423,813 filed Jun. 13, 2006, which is acontinuation of U.S. patent application Ser. No. 11/376,737, filed Mar.14, 2006, which claims the benefit of and is a non-provisional of U.S.Patent Application Ser. No. 60/661,746 filed on Mar. 14, 2005, which isincorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to wireless communications andmore particularly to coordinating different network uses of a commonwireless medium.

BACKGROUND OF THE INVENTION

Wireless communication among electronic devices has been increasing asthe benefits and conveniences of wireless communication become morepreferred. A wireless communication system or wireless network is oftendescribed as containing nodes (or more precisely, circuitry associatedwith the concept of a node) and a wireless medium (WM) over which thenodes' circuitry communicate to convey information. Where some action oractivity is described as happening at (or being done at) a node, itshould be understood that the electronic device and/or network interfacethat is at (or simply is) the node is the circuitry that is performingthe action or activity. For example, sending data from node A to node Bmeans transmitting a signal from circuitry associated with node A andreceiving that signal (or more precisely, the transmitted signalmodified by the medium) using circuitry associated with node B.

The information conveyed between nodes can be digital data and digitizedanalog signals, or other forms of information, but communication systemdesign often assumes that digital data is being conveyed and highernetwork layers interpret the data appropriately. For purposes herein, itis assumed that data exists at one node, is provided to lower networklayers, is conveyed to another node over a WM, is received by anothernode correctly or incorrectly and then is conveyed to upper networklayers at the receiver. In one model, two networked devices runapplications that pass data between themselves by having the sendingdevice's application convey data to an application layer of a networkstack, which conveys data to lower levels, ultimately to a medium accesscontrol (MAC) layer and a physical network (PHY) layer, and the processis inverted at the recipient.

To set up a wireless network, all that is needed is a plurality ofelectronic “node” devices capable of transmitting and receiving data ina manner understood by the two (or more) nodes involved in aconversation, with the node devices appropriately placed such that theycan communicate in the medium that exists between the devices. Themedium could be some type of dielectric material, but more commonly, themedium is the air space and objects (walls, chairs, books, glass. etc.)that are between devices or are positioned such that they have an effecton the signals transmitted between devices. Presumably, the node devicesare assigned unique identifiers to distinguish transmissions, but thismight not always be necessary. Examples of such unique identifiers areMAC addresses and IP addresses.

As the existence of various wireless media and their properties areknown and are not the focus of this disclosure, the medium is often justshown in the attached figures as a cloud. Thus, it should be understoodthat supplier of a set of two or more powered devices that cancommunicate supplies a wireless network; the wireless medium ispresumed.

Wireless communication systems can be categorized based on coveragerange, which in some cases is dictated by use. A wireless local areanetwork or “WLAN”, has a typical coverage range on the order of 300 feetand is useful for providing communications between computing devices insome (possibly loosely) defined space such as a home, office, building,park, airport, etc. In some modes of operation, one or more of the nodesis coupled to a wired network to allow other nodes to communicate beyondthe wireless network range via that wired network. In 802.11terminology, such nodes are referred to as “access points” and thetypical protocol is such that the other nodes (referred to as“stations”) associate with an access point and communication isgenerally between a station and an access point. Some wireless networksoperate in an “ad hoc” mode, wherein node devices communicate with eachother without an access point being present.

A personal area network or “PAN” is a short-range wireless network, withtypical coverage ranges on the order of 30 feet, usable to connectperipherals to devices in close proximity, thereby eliminating cablesusually present for such connections. For example, a PAN might be usedto connect a headset to a mobile phone or music/audio player, a mouse orkeyboard to a laptop, a PDA or laptop to a mobile phone (for syncing,phone number lookup or the like), etc. Yet another example of a wirelessPAN application is wireless medical monitoring devices that wirelesslyconnect monitoring hardware to a pager or similar read-out device. Yetanother example is a remote control that connects to a wireless-enabledelectronic device.

Some networks might fall in a gray area between a WLAN and a PAN, but inmany cases, a network is clearly one or the other. A personal areanetwork (PAN) is generally used for the interconnection of informationtechnology devices within the range of an individual person, typicallywithin a range of 10 meters. For example, a person traveling with alaptop will likely be the sole user of that laptop and will be the sameperson handling the personal digital assistant (PDA) and portableprinter that interconnect to the laptop without having to plug anythingin, using some form of wireless technology. Typically, PAN nodesinteract wirelessly, but nothing herein would preclude having some wirednodes. By contrast, a wireless LAN tends to be a local area network(LAN) that is connected without wires and serves multiple users.

Equipment connecting to a wireless communication system in general, andto a wireless PAN communication system in particular, is typically usedfor applications where power usage, weight, cost and user convenienceare very important. For example, with laptops, low-cost accessories arepreferable, and it is critical that the power usage of such accessoriesbe minimized to minimize the frequency at which batteries need to bereplaced or recharged. The latter is a burden and annoyance to the userand can significantly reduce the seamless user experience.

Weight and complexity are additional concerns in many wirelesscommunication systems. Particularly with mobile devices such as laptops,weight is a concern and the user would rather not have to deal with thehassle of carrying around a multiplicity of devices. Mobile devices aredevices that can be expected to be in use while moving, while portabledevices are devices that are movable from place to place but generallyare not moving when in use. The considerations for mobile devices alsoapply to portable devices, albeit sometimes with less of a concern. Forexample, with a wireless connection of a peripheral to a laptop, bothdevices are likely to be used while mobile or moved frequently andcarried around. Thus, weight and the number of devices is an importantconsideration. With portable devices, such as a small desktop computerwith a wireless trackball, as long as the total weight is below a user'scarrying limit, the weight is not as much a concern. However, batterylife is often as much a concern with portable devices as it is withmobile devices.

There are shades of grey between “portable” and “mobile” and it shouldbe understood that the concerns of mobile applications and portableapplications can be considered similar, except where indicated. In otherwords, a mobile device can be a portable device in the examplesdescribed herein.

Where a computing and/or communication device connects to a WLAN, ituses wireless circuitry that often times are already built into thecomputing device. If the circuitry is not built in, a WLAN card (such asa network interface card, or “NIC”) might be used. Either way, someantenna circuitry is used and power is required to run that circuitry.

Where a device also connects wirelessly to peripherals or other devicesover short links often referred to as forming a “personal area network”or “PAN”, circuitry is needed for that connection as well. Thiscircuitry is typically provided with an external interface unit that isplugged into or onto the device. For example, where the device is alaptop, the circuitry might be provided by a Universal Serial Bus (USB)dongle that attaches to a USB port of the laptop. The USB donglecontains the radio circuitry needed to communicate wirelessly over theshort wireless links.

In general, a wireless connection between two or more devices requiresthat each device include wireless network circuitry for conveyingsignals over the medium and receiving signals over the medium, as wellas processing/communication circuitry to receive, process and/or conveydata and/or signals to that wireless network circuitry. Theprocessing/communication circuitry could be implemented with actualcircuits, software instructions executable by a processor, or somecombination thereof. In some variations, the wireless network circuitryand processing/communication circuitry are integrated (such as with somePDAs, wireless mice, etc.) or are separate elements (such as a laptop asthe processing/communication circuitry and a network PCMCIA card as thewireless network circuitry).

For ease of understanding this disclosure, where it is important to makethe distinction between devices, a device that exists to providewireless connectivity is referred to as a “network interface”, “networkinterface device”, “wireless network interface device” or the like,while the device for which the wireless connectivity is being providedis referred to as a “computing device” or an “electronic device”notwithstanding the fact that some such devices do more than justcompute or might not be thought of as devices that do actual computingand further notwithstanding the fact that some network interface devicesthemselves have electronics and do computing. Some electronic devicescompute and communicate via an attached network interface device whileother electronic devices might have their network interface devicesintegrated in a non-detachable form. Where an electronic device iscoupled to a wireless network interface to a wireless network, it issaid that the device is a node in the network and thus that device is a“node device”.

An 802.11x (x=a, b, g, n, etc.) NIC (network interface card) or 802.11xbuilt-in circuitry might be used for networking an electronic device tothe outside world, or at least to devices at other nodes of a WLAN802.11x network, while using an external dongle or a similar interfacedevice with Bluetooth or proprietary wireless circuitry forcommunication between the computing device and the peripheral or otherPAN node.

A device that is equipped with an 802.11x-conformant network interfaceto the WM is herein referred to as a station or “STA”. In 802.11terminology, set of STAs constitutes a Basic Service Set (“BSS”). A setof STAs that communicate in a peer-to-peer configuration is referred toas an “802.11x ad-hoc” network or an independent BSS (IBSS). A set ofSTAs controlled by a single coordinator is referred to as an 802.11xinfrastructure network. The coordinator of a BSS is herein referred toas the access point or “AP”.

A typical access point device is wired to a wired network and is alsowired to an external source of electricity, such as being plugged into awall socket or wired to a building's power grid. For example, abuilding, an airport or other space people might occupy might have fixedaccess points mounted throughout the space to provide adequate networkcoverage for the purpose of providing access to the Internet or othernetwork for the people occupying the space, via their portable or mobiledevices. As such, access points are typically always on so that thewireless network is available whenever suitable portable or mobiledevices are carried into the space.

The use of different technologies for WLAN and wireless PAN connectivityincreases cost, weight and power usage (at the COORD side and/or the PERside), and impairs a seamless user experience. Those disadvantages couldbe resolved by equipping the peripheral or PAN nodes with 802.11xwireless circuitry, thus eliminating the dedicated PAN technologiesaltogether. However, PAN nodes are often very power-sensitive devices.They usually are battery-operated devices and their small form factorprohibits the use of bulky batteries with large capacity. Instead, smallbatteries with limited power capacity are used. Such peripherals cannottypically support the power usage requirements typical of WLAN wirelesscircuitry, such as 802.11x circuitry. A host of other difficulties arepresent in view of the optimizations, goals and designs of differingnetwork protocols.

Another drawback is that independent LANs and PANs may interfere if theyshare a common frequency band.

BRIEF SUMMARY OF THE INVENTION

In embodiments of wireless communication according to the presentinvention, a computing device is interfaced to a wireless personal areanetwork (PAN) in an environment wherein coexisting wireless local areanetworks (WLANs) might be present, and devices of the wireless PANcoordinate usage of the wireless medium with devices of the WLANs thatare active in the same space, using the same, or part of the same,wireless medium. Coordination is achieved by the use of a wireless PANcommunication protocol that is an overlay protocol that is onlypartially compliant with the WLAN protocol, but not entirely, in termsof power, frame contents and sequences, timing, etc. The WLAN might havean access device (infrastructure mode) or not (ad hoc mode). In eithercase, at least some of the WLAN devices would be able to interpret partof some PAN frames.

A given PAN device might also be a WLAN device, but it might also be thecase that all of the wireless PAN devices operate within the wirelessPAN. Coexisting WLANs can be 802.11x WLANs. The wireless PAN devicespreferably use a protocol that is at least partially understood bynearby WLAN devices such that the WLAN devices will sense that thewireless medium is busy and will appropriately defer. The partiallycompliant protocol might be a protocol optimized for PAN traffic anddevices.

To reduce interference, a computing device that is a coordinator in awireless PAN network might determine to signal a WLAN operating in thesame wireless networking medium such that devices therein defer accessto the WM so that communication can occur within the wireless PANnetwork, determine a length of time for PAN-computing devicecommunication, reserve the wireless medium for at least that length oftime and use that time for communicating with the wireless PAN usingprotocols that overlap with conventional WLAN protocols but are notnecessarily compliant.

Signalling to a coexisting WLAN and reservation of the common wirelessmedium can be implicit or explicit. Implicit signalling occurs when awireless PAN device transmits a frame within the wireless PAN networkusing a wireless PAN overlay protocol, but at a minimum those portionsof the overlay protocol that are required to trigger a nearby STA in acoexisting WLAN to defer accessing the WM are compliant with the WLANprotocol. A nearby STA in a coexisting WLAN, upon hearing an overlayprotocol frame, will understand at least enough of the overlay protocolframe to defer use of a common wireless networking medium. Explicitsignalling occurs when a computing device can join both networks,exchanges one or more frames in the WLAN network using the WLAN protocolto communicate times of wireless PAN traffic, and communicates withdevices in the wireless PAN network using a wireless PAN overlayprotocol during the times agreed on with the devices in the WLAN.

The secondary network (PAN) protocols might use 802.11x frames ormodifications thereof, with new frame arrangements, frame sequences etc.adapted for PAN needs.

The secondary network (PAN) protocols might use synchronization andtraffic scheduling methods to meet the power and latency requirements ofspecific wireless PAN applications. Such methods allow wireless PANdevices to agree on an inactivity time, during which at least part ofthe circuitry can be disabled, wherein disabling is such that less powerper unit time is consumed by the network circuit relative to powerconsumed when not disabled.

The secondary network (PAN) protocols might support connectivity statesthat are different from or an extension of connectivity states supportedby PWN (WLAN) protocols. Such connectivity states may be supported tomeet typical SWN needs. Examples of typical SWN needs might include butare not limited to (1) reducing the power consumption of the devices inthe SWN, (2) optimizing the network capacity, and (3) meeting thelatency requirements of a PER device. There may be different reasons forsupporting multiple connectivity states as well.

Other objects, features, and advantages of the present invention willbecome apparent upon consideration of the following detailed descriptionand the accompanying drawings, in which like reference designationsrepresent like features throughout the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating various devices operating as partof a primary wireless network (PWN), a secondary wireless network (SWN),or both, wherein the SWN operates using an SWN protocol that co-existswith the PWN protocol.

FIG. 2 is a block diagram illustrating a subpart of the elements of FIG.1, in greater detail.

FIGS. 3(a)-(d) comprise several examples of elements of a PWN and anSWN; FIG. 3(a) is a block diagram showing elements of a PWN and an SWNthat co-exist, but do not necessarily span the two networks; FIG. 3(b)is a block diagram showing specific objects that might be used as theelements of a PWN and an SWN; FIG. 3(c) is a block diagram of avariation of subparts wherein objects might span the PWN and the SWN;FIG. 3(d) is a block diagram showing further examples.

FIG. 4 is a block diagram of an example wireless PAN coordinator(“COORD”) that might also operate as a dual-net device that couldsimultaneously maintain connections with a PWN and a SWN.

FIG. 5 is a block diagram of a network card that might be used tointerface a COORD/dual-net device to the various networks.

FIG. 6 is a block diagram of software components that might comprisesoftware and/or logical constructs to interface applications with thenetworks supported by a COORD/dual-net device.

FIG. 7 is a block diagram of classes and objects that might be used inan interface between a network and applications.

FIG. 8 is a block diagram of an example of a PER device.

FIG. 9 is a diagram illustrating a reduced wireless medium reservationzone relative to two network spaces.

FIG. 10 is a timing diagram illustrating timing for a frame exchangeprocess.

FIG. 11 is a timing diagram illustrating timing for an alternative frameexchange process.

FIG. 12 is a timing diagram illustrating timing for a multi-PERcoordination process.

FIG. 13 is a timing diagram illustrating timing for an alternative frameexchange sequence for a multi-PER coordination process.

FIG. 14 is a schematic diagram illustrating steps of a direct linkhandshake.

FIG. 15 is a schematic diagram illustrating steps of a using a directlink setup between two STAs.

FIG. 16 is a state diagram for an embodiment of stateful operation of aCOORD (which might be used for a dual-net device or otherwise) and/or aPER.

FIG. 17 is a schematic diagram of frame formats usable for anon-standard HCCA frame.

DESCRIPTION OF THE INVENTION

The present disclosure describes methods and apparatus for operating asecondary wireless network (“SWN”) in the presence of a primary wirelessnetwork (“PWN”), including features, elements, configurations and/orprogramming that allow for co-existence of SWN devices in a space wherePWN traffic might occur, as well as features, elements, configurationsand/or programming that include coordination between a PWN and an SWN(or pluralities of these) such that a device might handle traffic foreach of the networks present.

For example, a computing device might have a common network interfacethat allows the computing device to be a node in the PWN and a node inthe SWN. In a particular example, a computing device is an 802.11x STAthat is a member of a PWN capable of associating with and communicatingwith an AP for that PWN (as well as possibly other devices in that PWN)using a network interface while also elements of that same networkinterface are used to simultaneously participate as a WPAN coordinator(“COORD”) to coordinate the SWN, such that the COORD can communicatewith members of one or more SWN without losing the COORD's connectivityto the primary network and using common hardware components to interfaceto both networks. Where a COORD is connectable to the PWN, it isreferred to as a “dual-net” device, as it coordinates communication overthe SWN such that it can be connected to both simultaneously, possiblyincluding steps that involve signaling within the PWN as part of SWNactivity (e.g., reserving the PWN to avoid interference before using theSWN).

In some instances, the COORD is not set up to connect to the PWN, but itstill performs the necessary actions to coordinate traffic for the SWNit coordinates, including performing actions that improve coexistence ofthe PWN and SWN.

In the general example, the computing device is a portable and/or mobilecomputing and/or communications device with some computing capability.Examples of computing devices include laptop computers, desktopcomputers, handheld computing devices, pagers, cellular telephones,devices with embedded communications abilities and the like. Examples ofperipheral devices include typical computer, telephone etc. accessorieswhere wireless connections are desired, but might also include lesscommon devices, such as wearable devices that communicate with otherdevices on a person or even to communicate with other nearby devices,possibly using the electrical conductivity of the human body as a datanetwork. For example, two people could exchange information betweentheir wearable computers without wires, by transmission through the air,or using their bodies and/or clothing.

The computing devices may interface to 802.11 WLANs or other wirelessnetworks to communicate with other network nodes, including nodesaccessible through wired connections to the wireless network (typicallyvia an access point). The computing devices also may interface to PANdevices over a personal area network (PAN), such as wireless headsets,mice, keyboards, accessories, recorders, telephones and the like. A widevariety of PAN devices are contemplated that are adapted for short-rangewireless communications, typically bi-directional and typically lowpower so as to conserve a PAN device's limited power source. Some PANdevices might be unidirectional, either receive-only or transmit-only,devices.

In a typical approach, where a STA needs to connect to more than onewireless network, the STA associates with one wireless network and thenwhen associating with another wireless network, it disassociates withthe first wireless network. While this is useful for a WLAN where a STAmight move out of one network's range and into the range of anothernetwork, this is not desirable when latency needs to be less than anassociation set-up time. The latency incurred with this switchingprocedure easily amounts to several hundreds of milliseconds.

In certain applications, it may be desirable for a STA to connect tomultiple networks without incurring long switching-induced latencies.For example, consider a typical PER device, that of a cordless mouse.Since update rates for a cordless mouse during normal operation are onthe order of 50 to 125 times per second, switching-induced latenciesinvolved with 802.11x association set ups are not acceptable.Furthermore, the switching overhead significantly reduces the STA'susable communication time, defined as the time that the STA is availableto transmit or receive data.

In a specific embodiment of the invention, a wireless peripheral like amouse, is attached to an 802.11x-enabled computing device like a laptopcomputer, using the 802.11x wireless circuitry inside the laptop, orconnected to the laptop via a NIC card. At the same time, the laptop maybe connected to the Internet via a regular WLAN network, using the same802.11x circuitry. Herein, a peripheral or PAN node will be referred toas “PER”. Multiple PERs can connect to a single wireless PAN. Thewireless device coordinating the wireless PAN is called the coordinator(“COORD”). Where the COORD is also able to connect to the 802.11xnetwork, the COORD is referred to as a “dual-net” device, since ithandles both networks. A typical dual-net device in this example is adevice that is a STA on an 802.11x network while also having wirelessperipherals used by applications running on that device.

While not always required, the PERs are power-sensitive devices. Itshould be understood that an object labeled “PER” need not be aperipheral in the sense of an object with a purpose to serve aparticular purpose, but rather an object that performs the behaviorsherein referred to as behaviors of a PAN node. For example, a printercan be a PER when it is connected to a desktop computer via a PAN, butsome other device not normally thought of as a peripheral can be a PERif it behaves as one.

Examples of the concepts and disclosures provided above will now befurther explained with reference to the figures. In the figures, likeitems are referenced with a common reference number with parentheticalnumbers to indicate different instances of the same or similar objects.Where the number of instances is not important for understanding theinvention, the highest parenthetical number might be a letter, such asin “100(1), 100(2), . . . , 100(N)”. Unless otherwise indicated, theactual number of items can differ without departing from the scope ofthis disclosure.

Specifically, FIG. 1 illustrates various devices operating as part of aprimary wireless network (PWN) 100, a secondary wireless network (SWN)(such as 114 or 116), or both. In the figure, an access point (AP) 110supports an infrastructure mode for PWN 100, coupling various stationsto the network allowing, for example, network traffic between a stationand a wired network 112. By communicating with the AP, a station canretrieve information from the Internet and exchange data with otherstations that may or may not be part of the Basic Service Set (BSS)managed by the AP.

As shown in the example, the stations present are STA1, STA2, STA3 andSTA4. Each station is associated with a node in PWN 100 and has thenecessary hardware, logic, power, etc. to be a node device in PWN 100.Station STA1 also coordinates SWN 114 as the COORD for that networkshown comprising PER1, PER2 and PER3. Likewise, station STA4 coordinatesSWN 116 as the COORD for the network comprising STA4, PER10 and PER11.In FIG. 1, each node device is shown with an antenna to indicate that itcan communicate wirelessly, but it should be understood that an externalantenna is not required.

Other network components and additional instances might also be present.For example, more than one AP might be present, there might be overlapsof BSSes and other network topologies might be used instead of the exactone shown in FIG. 1 without departing from the scope of the invention.Examples used herein for PWN 100 include 802.11x (x=a, b, g, n, etc.),but it should be understood that the primary wireless network may wellbe another network selected among those in present use or available whenthe primary wireless network is implemented.

In this example, the secondary wireless networks are assumed to be usedfor PAN functionality. The PAN can be used for, but is not limited to,fixed data rate applications where exchange of data can be scheduled andthe amount of data to be exchanged is known and a single dual-net devicemight interface with multiple PERs. Because the dual-net device may be aregular STA in the first WLAN, it can power-down as needed withoutproblems, unlike an access point. However, since it is also the COORD,peripheral communication could be lost if the peripheral is powered upbut the dual-net device/COORD is not. This can be dealt with usingmutually agreeable inactivity periods.

FIG. 1 shows, at a high level, the interplay among various nodes ofvarious networks. FIG. 2 illustrates a subpart of the elements of FIG.1, illustrating in greater detail. In this figure, AP 110 is coupled towired network 112 via cable 120 and might communicate using any suitablewire-based networking protocol. On the other side, AP 110 transmitssignals to a station device, in this case a laptop 122, using the AP'santenna and those signals are received by laptop 112 using its antenna.Signals can also flow in the other direction. Such communications wouldbe done according to a PWN protocol, such as an 802.11x protocol.

Laptop 122 (a dual-net device in this example) in turn can communicatewith the peripherals shown, in this example a wireless mouse (PER1) 124and a wireless printer (PER2) 126. It may be that power for wirelessprinter 126 comes from an external power outlet, in which case powerconsumption might be less of a concern than with mouse 124 if itoperates on battery power. Nonetheless, both peripherals might use thesame power-saving protocol. Power conservation might also be performedon the dual-net device, for example, when it is a laptop.

FIGS. 3(a)-(d) comprise several views of network layouts of elements ofa PWN and a SWN.

FIG. 3(a) is a block diagram showing wireless elements that might beoperating in a common space 300 such that they share a wireless mediumor parts of it. In the description that follows, the examples assumethat the range of an access point, AP 301, is the common space 300. Inother examples, the common space is the range of the AP and STA devicesin the AP's BSS, or some other variation. As shown in FIG. 3(a), AP,STA1, STA2 and STA3 form the primary wireless network PWN, while devicesSTA4, PER1, PER2, and PER3 form the secondary wireless network SWN. STA4is the master for the SWN. Note that STA4 need not be associated as aSTA with AP 301.

FIG. 3(b) illustrates a more specific example. In that figure, PWN ismanaged by AP 301 and has node devices 302(1) and 302(2) (laptops inthis example figure) associated with the PWN. A mobile phone 304 is themaster for the SWN that includes a headset 306. Mobile phone 304 maywell not have the capability to join PWN, but since the PWN and SWNshare the same wireless medium, preferably mobile phone 304 has COORDfunctions that would enhance coexistence of PWN devices and SWN devices.AP 301 is also coupled to a wired network 303.

The various protocols used between devices are marked as “PP” for PWNprotocol, which might be an 802.11x protocol or the like and “SP” forSWN protocol, which might be a modified 802.11x protocol, an overlayprotocol, or the like. As used herein, an overlay protocol is an SWNprotocol that has elements that are reuses of elements of a PWN protocolto provide one or more advantages, such as ability to use some commonhardware components for both networks, the ability to communicate in theSWN without having to disassociate with the PWN, the ability to signalin the SWN with signals that are understood by SWN devices but are suchthat they are, if not understood, are acted upon by PWN devices toprovide desirable actions. For example, an overlay protocol might besuch that a PWN-only device that hears an SWN packet will be able todecode the packet enough to determine that the packet is not for thePWN-only device and also determine how long the wireless medium will bebusy with SWN traffic so that the PWN-only device can appropriatelydefer.

Of course, if all of the PWN devices and SWN devices had the sameconstraints and could support a wider-area network standard protocol,then perhaps all of the devices would just be nodes in one network anduse that network's protocol for contention, coordination, and the like.However, where one-size-fits-all does not work, it is preferred thatsome sort of coexistence enhancement occur.

FIG. 3(c) is a block diagram of another topology example, wherein atleast one device spans a network. In that example, AP 301 communicateswith an 802.11x-enabled Personal Digital Assistant (PDA) 305 and an802.11x-enabled mobile phone 307, while phone 307 acts as a COORD for asecondary network to interact with a wireless headset 306. In somevariations, PDA 305 and phone 307 might communicate in ad hoc mode. Asan example of the use of these elements, phone 307 might be used tosimultaneously conduct a wireless Voice-over-IP (VoIP) call and attachwireless headset 306.

FIG. 3(d) is a block diagram illustrating a more complicated example. Asshown there, AP 301 is coupled to wired network 303 and is wirelesslycoupled with its associated stations: laptops 302(1) and 302(2), as wellas a laptop 310 that is a COORD for a secondary wireless network, SWN1.Laptop 310 coordinates SWN1, which includes mouse 320, keyboard 322 andmobile phone 304. Mobile phone 304 can in turn be a COORD for anothersecondary wireless network, SWN2 while being a PER in SWN1. As shown,the communications with AP 301 use a PWN protocol, such as an 802.11xprotocol, while the communications among devices in SWN1 and SWN2 aredone using the SWN protocol. As explained elsewhere herein, there aremany benefits of using an SWN protocol such as an 802.11x overlayinstead of an all 802.11x protocol and by suitable design of the SWNprotocol, the SWNs and the PWN can co-exist and, in the case of dual-netdevices, can reuse common network interface devices for the dual-netdevice's participation in both a PWN and an SWN.

In the example of FIG. 3(d), it may be expected that mouse 320, keyboard322, mobile phone 340 and headset 306 are not programmed for, and/or donot have circuits to support, use with an 802.11x primary network, butnonetheless they might use an SWN protocol that has many aspects incommon with an 802.11x protocol, modified to accommodate the differentneeds of SWN devices while providing a measure of co-existence. Thenetwork interface for a dual-net device might comprise standard hardwarefor interfacing to the PWN and software to control that standardhardware to use it for SWN protocol traffic. Thus, with the selection ofthe SWN protocol such as those described or suggested herein, SWNsupport can be added to a computing device without requiring any newhardware.

FIG. 4 illustrates an example of the internal details of a COORD device.As explained herein, such devices might include laptops, desktopcomputers, terminals, MP3 players, home entertainment systems, musicdevices, mobile phones, game consoles, network extenders or the like.What is shown is one example. In this example, a COORD device 400 isshown comprising a processor 402, the memory 404, program and softwareinstruction storage 406, a wired input/output interface 407 fordisplays, keyboards and the like, an internal clock 408, and a networkI/O interface 410, each coupled to a bus 412 for intercommunication.Network I/O interface 410 is in turn coupled to a network card 414,which includes its own circuitry such as an internal clock 416 and othercomponents not shown. In some cases, the network card is not distinctand in some cases there might not even be much hardware associated withthe networking function if it can be done by software instructions.

Program and software instruction storage 406 might comprise program codememory 420 and disk drive 422. Program instructions for implementingcomputing, communication, etc. functions, as well as networkinterfacing, can be stored in program code memory 420 and might beloaded in there from instructions stored on disk drive 422. Program codememory 420 might be just a portion of a common memory that also hasmemory 404 as a portion. For example, both memories might be allocatedportions of RAM storage so that instructions and data used by programsare stored in one memory structure. With a general purpose,network-centric, signal processing-centric or other style of processor,functional modules that might be illustrated by blocks in a blockdiagram might be implemented entirely in software, embodied only in codestored in computer readable media. However, when executed as intended,the processor and the stored instructions perform the functions of thosemodules. For example, a device might be described as having a networkstack that performs certain functions, but the network stack might notbe represented in individual hardware elements.

FIG. 5 illustrates an example of a network card 500, shown comprisinginterface circuits 502 for interfacing network card 500 to a computingdevice (not shown), control/datapath logic 504, baseband modem circuitry506, an RF section 508, an antenna 510 and a card clock circuit 512.Control/datapath logic 504 is configured to send and receive data to andfrom the computing device via interface circuits 502, send and receivedata to and from baseband mode circuitry 506 and process that sent orreceived data as needed. Card clock circuit 512 might provide circuitclocking services as well as real-time clock signals to various otherelements of network card 500. Note that logic elements shown anddescribed might be implemented by dedicated logic, but might also beimplemented by code executable by a processor. For example, some of thecontrol/datapath logic's functionality may be implemented in softwarerather than hardware. An example processor is the ARM7 processoravailable from ARM Limited of London, England.

In operation of an example network card, power might be supplied viainterface circuits 502 as well as providing a wired datapath for datainto and out of the network card. Thus, when the connected computingdevice desires to send data over the network(s) supported by the networkcard, the computing device sends the data to an input circuit ofinterface circuits 502. The input circuit then conveys the data tocontrol/datapath logic 504. Control/datapath logic 504 may format thedata into packets if not already so formatted, determine the PHY layerparameters to use for the data, etc., and possibly other processesincluding some well-known in the art of networking that need not bedescribed here in detail. For example, logic 504 might read a real-timeclock from card clock circuit 512 and use that for data handling orinclude a real-time clock value in header data or other metadata.

Logic 504 then outputs signals representing the data to baseband modemcircuitry 506 which generates a modulated baseband signal correspondingto the data. That modulated baseband signal is provided to RF section508. The timing of output of signals of logic 504 and other parts of thenetwork card might be dictated by a timing clock signal output by cardclock circuit 512. RF section 508 can then be expected to output an RF,modulated signal to antenna 510. Such output should be in compliancewith requirements of nodes of the networks with which the computingdevice is associating.

For example, if the computing device is expecting to be associated as anode in an 802.11b network, the signal sent to antenna 510 should be an802.11b compliant signal. Also, the control/datapath processes shouldprocess data in compliance with the requirements of the 802.11bstandard. Where the computing device is expecting to be a dual-netdevice, the signals sent should be compliant with the protocols and/orstandards applicable for the network to which the signals are directed,and be done in such a way as to deal with the fact that whilecommunication is happening among devices of one network (such as theprimary wireless network or the secondary wireless network), thosesignals might be heard by devices that are only devices in a differentnetwork (such as the secondary wireless network, the primary wirelessnetwork or other network) and the signals should be such that devicescan at least co-exist.

Where the computing device is a dual-net device, its network card wouldprovide signals for the primary network and the secondary network. Inone example mentioned herein, the primary network is an 802.11x networkand the computing device is a STA node for that network and thesecondary network is a PAN and the computing device is the COORD forthat network. In some implementations, network communications arehandled using a software platform that supports network applications.

In some embodiments, wherein 802.11x or other PWN protocols do not needto be supported, the built-in wireless circuitry or network card couldbe designed to handle only SWN protocols, as would be the case where thenetwork comprises all devices that are capable of handling SWN protocolcommunications. Examples of such protocols include protocols thatoperate between devices built by H-Stream Wireless, Inc. to communicateusing an H-Stream protocol such as their HSP protocol. In someHSP-enabled devices, the network logic can be entirely represented withsoftware that accesses the RF section of a device that might be ageneric network interface, possibly using additional hardware. However,where both ends are HSP-enabled devices, they might use their ownhardware and control it at whatever level is needed for bestperformance.

FIG. 6 illustrates a platform 600 as it might be present in a dual-netdevice, that represents software and/or logical constructs that togethercan be thought of as logical elements available for processing datawithin the computing device. As such, they need not be implemented asseparate hardware components or distinct software components, so long astheir functionality is available as needed. Other variations arepossible, but in the layout shown, applications and system services(shown as block 602) are programmed to interface to various stacks, suchas an IP networking stack 610 (sometimes referred to as an “IP stack”),a peripheral stack 612 (USB, HID, audio, etc.), a non-IP stack 614 (forIEEE 1394 interfacing) or other stack 616. For example, an applicationsuch as an HTTP browser might expect to communicate using TCP/IP andthus that application would have been configured to communicate with thecomputing device's IP stack.

A convergence platform can be added between an 802.11x stack and thedifferent drivers to enable multi-protocol support, expose andcoordinate access to specific MAC service primitives and coordinate thepriority handling in Quality-of-Service (QoS) sensitive applications.This convergence platform can be a separate software layer or can alsobe integrated within the 802.11x stack.

For certain stacks, additional services may be required that might notbe supported inside the 802.11x stack. If that is the case, such overlayprotocol services may reside either inside the convergence layer or inbetween the convergence layer and the respective stack. As an example,communication with peripherals may require protocol services in additionto the protocol services provided by the 802.11x stack in order to meetthe power and latency requirement typical of such applications. Suchprotocol services may be part of the convergence layer, or may reside inbetween the convergence layer and the Peripheral Interconnect Stack. Ofcourse, as an alternative, the 802.11x stack may have been adapted tosupport such services.

Each of the stacks 610-616 is shown coupled to a convergence layer 620,which provides the necessary and/or optional conversions of data,protocol, timing, etc. so that each of the higher level stacks 610-616are interfaced to an 802.11x stack 622. 802.11x stack 622 can theninterface to the computing device's network card (or other networkcircuitry). In this manner, for example, stack 622 might handle abrowser's traffic that goes through IP stack 610 while also handling amouse interface whose traffic goes through peripheral stack 612. Notethat with a single 802.11x stack, a single network interface can carrytraffic for more than one higher-level stack. The single networkinterface needs to be tuned to deal with the different requirements ofthe different stacks.

Communication protocols can be implemented with drivers or firmware thatis installed on the dual-net device/COORD. The drivers or firmware mightcomprise an 802.11x peripheral service function (e.g., for implementingthe services of the overlay protocol that are not supported inside the802.11x stack), which can be application-independent, and an adapterdriver to connect the 802.11x stack and 802.11x peripheral servicefunction to the appropriate driver inside the dual-net device/COORDplatform. The adapter driver may be device class or device specific.

An example of this is illustrated in FIG. 7 for a wireless PAN where amouse is connected over the WM to the standard HID class driver in a PCrunning on the Windows (or other applicable Operating System (OS)). Thedriver or firmware resides between the 802.11x stack 706 and thestandard HID class driver 703. In a specific implementation, the driveror firmware can constitute an HID adapter driver 704 and an 802.11xperipheral bus driver 705.

Other variations of what is shown in FIG. 7 are possible. For example,the 802.11x peripheral service function might connect up to the MOUHIDdriver 702 directly. In that case, the HID adapter driver is written asan HIDCLASS miniport driver. This driver then layers under the MOUHID702 and MOUCLASS 701 drivers and allows mouse data to be injected intothe operating system.

Alternatively, the adapter driver may connect to the USB stack instead.The adapter driver may, for example, be written as a virtual USB busdriver and connect up to the standard USB stack available as part of theoperating system or operating system modifications. Depending on thespecific implementation, the adapter driver may connect at differentlayers into the USB stack.

In specific embodiments, the 802.11x peripheral service function andadapter driver may be combined in a single driver. Alternatively, twoseparate drivers may be used and a private interface might be definedand used between both drivers.

The adapter driver receives the 802.11x frames from the 802.11xperipheral service function that are intended for the higher layerdriver (e.g., MOUCLASS driver). Similarly, the adapter driver receivesframes from the higher layer driver that are to be transmitted to a PERusing the 802.11x circuitry. The adapter driver and 802.11x peripheralservice function generate and decode the necessary packet header forrunning a specific application, like the HID protocol, over an 802.11xdata channel. For example, it removes the 802.11x-specific MAC headerand performs the necessary manipulation to transform it in the correctformat to be passed on to the respective class driver.

FIG. 8 is a block diagram illustrating an example of what might be thecomponents of a PER device. As shown, PER 800 comprises a wirelesstransceiver 802 coupled to sensor/stimulus elements 804 and antenna 806.Additional components, such as a filter, a balun, capacitors, inductors,etc., may be present between wireless transceiver 802 and otherelements. Generally, wireless transceiver 802 allows other networkeddevices to understand results of sensing (in the case of a PER that doessensing, such as a mouse, microphone, remote condition sensor, etc.)and/or to specify stimulus (in the case of a PER that outputs visual,audio, tactile, etc. outputs, such as a printer, headset, etc.). Itshould be understood from this disclosure that PER can be a wirelessinput and/or output device and in many cases, the wireless transceivercan be designed independent of the particular input and/or output.

FIG. 8 also shows a battery 810 and a clock circuit 812. Battery 810provides power for wireless transceiver 802 and elements 804 as needed.As weight and portability are likely to be important in the design ofthe PER, battery consumption will often have to be minimized for a gooddesign. Clock circuit 812 might provide real-time clock signals as wellas providing circuit timing clock signals.

As shown, wireless transceiver 802 comprises interface circuits 820,control/datapath logic 822, a baseband modem 824, and an RF section 826.Control/datapath logic 822 might be implemented with circuitry thatincludes a central processing unit (CPU) 830 and memory 832 for holdingCPU instructions and variable storage for programs executed by CPU 830to implement the control/datapath logic. Control/datapath logic 822might include dedicated logic wherein CPU 24 and memory module 25implement the portion of the communication protocol that is notimplemented in the dedicated control and datapath logic. The CPUinstructions might include digital signal processing (DSP) code andother program code. The other program code might implement MAC layerprotocols and higher-level network protocols.

Clock circuit 812 might include a crystal oscillator. Clock circuit 812might be aligned with clocks in other network devices, but the clocksmay drift over time relative to each other.

Although not shown, other components like capacitors, resistors,inductors, filters, a balun, a Transmit/Receive (T/R) switch, anexternal power amplifier (PA) and an external low-noise amplifier (LNA)may also be included in PER 800.

Wireless transceiver 802 might be configured so as to communicate overthe physical layer (PHY) of a standard IEEE 802.11-compliant circuitchip. Wireless transceiver 802 may be an embedded System-on-Chip (SoC)or may comprise multiple devices as long as such devices, when combined,implement the functionality described in FIG. 8. Other functionality, inaddition to the functionality of FIG. 8 may also be included. Wirelesstransceiver 802 might have the ability to operate, for example, in theunlicensed 2.4-GHz and/or 5-GHz frequency bands.

One or more of the techniques described below might be needed to dealwith the characteristics of a wireless PAN that differ from a WLAN, orjust to improve performance of the devices in the networks.Modifications that create an overlay protocol, herein referred to as thePER service function, are described or suggested herein. In some cases,a computing device is able to join the WLAN and the wireless PAN (andeven at the same time), while in other cases, a computing device is onlyable to join the wireless PAN. In either case, the same or a similaroverlay protocol might be used to obtain the benefits thereof. Where thecomputing device is able to join both, the overlay protocol ispreferably such that the same networking hardware can be used for thecomputing device to join both networks.

WM Reservation

Power conservation may tend to be more critical in a PER device than ina COORD device. One technique described herein for conserving powerinside a PER device is to use lower transmit power and relax the rangerequirements for a transmitter below that which would be acceptable foran 802.11x transmission. This reduces the reception range of the PER'ssignal, but in most cases, the COORD is close enough to the PER to getthe signal and this is not an issue.

If the transmission and receive range of one or more members of a SWNare reduced to conserve power, frames transmitted by the PER might notbe detectable by members of the PWN and communication among members ofthe PWN might not be detected by the PER. This can lead to interferencebetween both networks, especially if both networks operate in the samefrequency band and on the same channel. This can be addressed by usingdifferent frequency bands or channels, but can also be dealt with usinga common band or set of bands and a common channel or set of channels.One such coordination method comprises a novel WM access procedure wherea powerful STA, like the dual-net device, reserves the WM for a lowpower node, like the PER. The WM reservation would be heard by devicesin a primary network that could not be reached by the PER.

In a specific embodiment, a COORD might determine a length of time forcommunication with a PER, transmit an 802.11x frame with the properfields (e.g., duration value) set so as to reserve the WM for at leastthat amount of time, and listen for a response frame from respectivePER. The frame transmitted by the COORD might be an actual 802.11x frameor a modification thereof. In any case, the frame arrangement shall besuch that STAs in nearby WLANs upon reception of such frame from COORDdefer access to the WM for at least the length of time specified by theframe. In addition, the frame arrangement is such that it can besuccessfully received by a PER. A PER, upon reception of such frame canrespond with a response frame immediately or after a specified turnaround time. In any case, a PER can respond without requiring a separateWM arbitration or WM reservation. As long as the length of the responseframe does not exceed the length of the WM reservation made by theCOORD, this communication can happen without interference from a nearbyWLAN, independent of whether or not the PER is able to reach the primarynetwork WLAN devices.

In a slightly different embodiment, a dual-net device might determine atime and a length of time for communication with PER devices in its SWN,signal to the PWN using the PWN (WLAN) protocol such time and length oftime, and communicate with PER devices during the periods of time agreedupon with the PWN. The signalling to the PWN can occur once prior to orat the start of a series of SWN communication events. As an example, ifthe SWN communication events are periodic, the dual-net device and PWNdevices may at one point in time agree on a start time and recurrenceperiod for WSN communication events. Alternatively, the signalling tothe PWN might occur prior to or at the start of each WSN communicationevent. Variations are also possible, where specific portions of thesignalling to the PWN occur at the start or prior to the start of aseries of communication events, whereas additional signalling is done ator prior to the start of each WSN communication event.

In the example where the PWN is an 802.11x WLAN network, signalling ofSWN communication events to the PWN can be done by using features andfunctionality that are supported by the 802.11x WLAN protocol, yet usesuch features and functionality in a different arrangement and for adifferent purpose, that is to accommodate reliable communication in acoexisting power-sensitive secondary wireless network.

As an example, the 802.11(e) WLAN protocol supports a channel accessmechanism, called Hybrid coordination function Controlled Channel Accessor “HCCA” that allows an AP in an 802.11 WLAN to coordinate contentionfree media use and allows the scheduling of WLAN traffic, as isdesirable for high Quality-of-Service (“QoS”) applications. HCCA is apolling-based mechanism, where a STA can set up a Traffic Stream (“TS”)with the AP of its BSS.

As part of the TS set-up, polling times and polling intervals arenegotiated and agreed upon between the AP and the STA. The AP can accessthe medium in a prioritized manner with respect to other STAs usingbasic access mechanisms, and as such has more control over the use ofthe WM. Once the AP has taken control of the WM, it can poll the STA atthe agreed upon time and grant the STA a transmission opportunity(“TXOP”) by making an adequate WM reservation for communication with theSTA. The HCCA mechanism might be used by a dual-net device to set up aTS with the AP of its PWN. It can then make use of the TXOPs and relatedWM reservations granted by the AP to communicate with PER devices in itsSWN. The dual-net device can communicate the QoS requirements of theattached PER to the AP (e.g., during a TS set up), “pretending” it to berequirements for itself. However, when granted the TXOPs by the AP itcan use these to conduct polling of and communication with devices inits SWN and as such meet the QoS requirements of the PER devices in itsSWN.

In certain embodiments, it may be desirable to only reserve the wirelessmedium in a limited radius around the SWN network to allow other devicesto communicate or operate without concern over the reservation. This maybe desirable to increase the capacity of the wireless medium. To achievethis, the COORD or dual-net device reserves the WM by transmitting aframe at a reduced transmission power, compared to the transmissionpower it normally uses for communication within the PWN. As an example,by reducing the transmission power for the WM reservation frame from 20dBm to 0 dBm, the range over which the WM will be reserved is typicallyreduced from hundreds of feet to tens of feet. This is illustrated inFIG. 9.

FIG. 9 illustrates wireless networks wherein a primary network 902 iscoordinated by an AP 904. Five STA devices (STA1 through STA5) are shownwithin primary network 902. A secondary network 906 is shown, wherein alaptop 908 is a dual-net device, in that it acts as a COORD forsecondary network 906 and as a station STA1 in primary network 902.

PER 910 is within secondary network 906. Laptop 908 issues a reducedpower WM reservation (or PER 910 does), to alert devices within range912. In the example shown, STA2 and STA3 hear the reservation and defer,but STA4 and STA5 do not fall within the reservation range of COORD 908.Thus, STA4 and STA5 can continue to communicate with AP 904 in primarynetwork 902. In such a configuration, secondary network 906 takes lesscapacity away from primary network 902. If the transmission range of aPER is reduced to conserve power, this approach can be implementedwithout causing significant interference between the secondary networkand far-away STAs in the primary network.

With only a “local” reservation of the WM, it is very well possible thatthe AP does not detect that reservation and may try to send a frame tothe COORD, since it is a STA on the PWN. The odds of that happening arepretty low though, since the COORD is only communicating with a PER fora very short time. If this collision happens, the AP will not get an ACKand will resend at a later time.

To increase the capacity of the common wireless medium, a novel methodcan be applied, where a COORD in a SWN adjusts the range over which itreserves the WM based on activity in the PWN or activity in separatenearby SWNs. As an example, if a lot of traffic is detected, a COORDmight decide to reduce the transmission power for signalling to the PWN,so that fewer devices in nearby wireless networks are affected by the WMreservation. If the COORD is a dual-net device, it may communicate withthe AP of its PWN to receive information about current WM activity,bandwidth usage, desirable transmission powers and WM reservation rangesetc.

Synchronization and Traffic Scheduling

Another technique for conserving power is to power off a portion or allof the circuitry in one or both of the PER and COORD during quiescenttimes, preferably coordinating a wake-up time so that the devices cancheck in with each other, to find pending data, synchronize clocks, etc.In many wireless PAN applications, it is important to minimize the powerusage not only inside the PER but also inside the COORD. This istypically the case when the COORD is also a battery-operated device. Anexample of such wireless PAN is the attachment of a wireless peripheralto a laptop. Another example is the attachment of a headset to a mobilephone or PDA. It is important to minimize the power usage inside thelaptop, mobile phone or PDA, since that determines how long such devicecan be used before a recharge is needed.

802.11x WLAN network power saving techniques are typically found only inthe STA devices, as most access points are wired for electricity anddata. For example, in the BSS shown in FIGS. 1-2, power savingtechniques might be implemented inside the STAs but the AP stays awakeall the time. A novel method comprises a synchronization procedurewherein a frame exchange sequence occurs between the COORD and the PER,in combination with a scheduling method to coordinate traffic between aPER and its COORD. In specific embodiments, a COORD communicates to aPER timing information of its local timer as well as information abouttimes of desired communication with the PER referenced to its localtimer. A PER, upon reception of such information can synchronize itstimer to the timer of the COORD and based on the information receivedfrom its COORD can determine at what time a communication event with itsCOORD is scheduled to take place. The start of a scheduled communicationevent is herein also referred to as the start of a Service Period. Inbetween communication events, both the COORD and PER can power down aportion or all of their circuitry to conserve power. At the start of ascheduled communication event, or slightly before the start of ascheduled communication event, both the COORD and PER power up thenecessary circuitry and exchange frames using an overlay protocol thatavoids interference with PWN STAs that might coexist in the samewireless networking space. With synchronization and scheduling, powersaving can occur at both ends of the link.

When the COORD is a dual-net device (i.e., it is also a STA in a PWN)and that dual-net device is in power-save mode in its primary network,it is critical that the appropriate circuits be powered up in time forcommunication with the PER, in order to ensure reliable communicationand accurate timing of frame transmissions. Traditionally, when a STAreceives a wake-up request, the STA powers up, and an empty data framewith the power management bit cleared is sent to the AP, to notify theAP of the change in its power save mode. Where the STA is a COORD andthe wake-up request is triggered by the secondary network, there is noneed to notify the primary network's AP of a change in power-save mode.

This “pseudo-power-save mode”, where the necessary circuits are poweredup to transmit and receive data but the AP of the primary network is notnotified of a change in power-save mode has the advantage that the APwill not attempt to send any pending traffic for that STA. Ideally, thedual-net device's circuits are powered on and off in synchronizationwith the PER medium access times. Whether it is possible to power downthe dual-net device's circuits in between data exchanges depends on thehardware and firmware implementation of the IEEE802.11 MAC and PHY, andthe duration of the pre-negotiated communication intervals.

It is possible that a COORD or dual-net device cannot get access to theWM for extended periods of time because of traffic on the PWN. This canintroduce latency problems and may result in additional powerconsumption as the PD may be kept awake waiting for extended periods oftime for the WM to become idle. If the COORD is a dual-net device it cancommunicate with the AP of the PWN, retrieve information from AP relatedto scheduled traffic streams and other forms of AP or STA activity so asto be able to track the activity on the PWN, and arrange thecommunication events with devices in its SWN when the PWN is expected tobe idle. As an example, if the PWN is an 802.11(e) network, a dual-netdevice may inquire information about the AP's Controlled Access Phase(CAP) and schedule communication events with PERs in its SWN so as toavoid the AP's CAP.

Frame Sequences

In a specific embodiment, a COORD and PER communicate at mutually agreedupon time intervals, herein referred to as Service Intervals. A ServiceInterval (“SI”) is defined herein as the interval between the start oftwo successive service periods (“SPs”). A service period (SP) is definedherein as a contiguous time during which one or more attempts is made tocommunicate one or more messages from a master device to a slave deviceand/or a slave device to a master. In general, it is expected thatduring an SP, both devices are attempting to communicate with each otherby either transmitting a packet or listening for a packet to betransmitted by the other device. It is possible that there are smallinactivity times in between packet exchanges, but such inactivity timesare typically significantly shorter than the SI. The service intervalmay be a constant value or can be irregular from service period toservice period. A service period may always be a fixed length or mayvary from service period to service period. As an example, a masterdevice and a slave device may have to agree on timing so that they canpower down some or all of their circuitry between SPs. In that case, themaster and slave device preferably ensure that they power up thenecessary circuits at, or slightly prior to, the start of an SP.

The start of a Service Interval (“SI”) is established, mutually agreedupon and adopted by both the COORD and PER as part of a synchronizationand traffic scheduling method that is part of the wireless PAN overlayprotocol. With synchronization and traffic scheduling, power saving canoccur at both ends of the link. The period of time during which framesare exchanged is hereafter referred to as the Service Period (or “SP”).

The frame exchange is illustrated in FIG. 10. As shown there, at thestart of an SP, T0, the COORD and PER are programmed to start the frameexchange. If power-save modes are implemented in the COORD or the PER, awake-up request will be issued prior to T0, to ensure that all necessarycircuits are powered up at time T0. At time T0, the COORD gains accessto the WM. Access to the WM can be obtained through various methodsincluding but not limited to WM contention, a priority access scheme(e.g., if the WM is detected to be busy, the COORD waits for a length oftime, but this length of time is shorter than the amount of time otherdevices have to wait) or a scheduled access scheme where slots of timeare pre-allocated such that no contention is required.

It is also possible that a different device, such as for example the APof the COORD's PWN gains access to the WM using basic contention or aprioritized access scheme and grants a transmission opportunity or“TXOP” to the COORD, which the COORD can then use to communicate withPERs in its SWN. In any case and independent of what access mechanism isused, upon gaining access to the WM, the COORD transmits a first frame(Frame 1), hereafter referred to as a “downlink frame”. If the COORDuses WM contention to gain access to the WM, the downlink frame may betransmitted using priority queues available inside the COORD. Forexample, the downlink frame may be transmitted using the highestpriority queue. The highest priority queue might be the priority of VoIPpackets (e.g., AC_VO), but in some cases it might not be necessary, notbe convenient or not be possible to use the highest priority queue.

The frame format of the downlink frame is such that it reserves the WMfor the subsequent frame transmission by the PER. As an example, if thedownlink frame is an 802.11x frame or a modification thereof, theduration field in its header might have been increased to reserve the WMfor at least the subsequent frame transmission by the PER. The frametransmitted by the PER (frame 2) is hereafter referred to as the “uplinkframe”. The sequence of FIG. 10 assumes that the COORD has sufficientinformation to determine an appropriate WM reservation for thesubsequent uplink frame. As an example, the COORD and PER may haveexchanged information about a typical uplink frame length (e.g., datasize) during an earlier communication. In addition, COORD and PER areaware of the other and have knowledge of critical communicationinformation such as each other MAC addresses; encryption keys and thelike. Such critical communication information may have been exchangedduring an earlier communication.

In case of data traffic from the COORD to the PER hereafter referred toas “downlink data” (e.g., headset application), or in case additionalinformation (e.g., management or control information) needs to becommunicated to the PER, such data and/or information may also beincluded in the downlink frame.

A pre-defined time later, such as one short interface space (“SIFS”)later, the PER responds with an uplink frame containing the data and/oradditional information (e.g., management and/or control information)from the PER. Optionally, the COORD can acknowledge reception of theuplink frame, which can be one SIFS later. Alternatively, regular mediumaccess procedures (e.g., contention) may be followed to transmit theACK, or the ACK may be included with communication in the next SP. TheACK may be a frame in an 802.11x ACK frame format, or a differentformat, as defined by the wireless PAN overlay protocol.

The duration of the WM need not be fixed and can vary. For example, thetime to send ACK may, may not or may partially be included. Othervariations may also be possible. The WM reservation is preferablysufficient to allow a protected transmission of the uplink frame by thePER device without requiring a contention for the WM by the PER device.

If no downlink data/information is included with the downlink frame(e.g., because the downlink frame format does not allow for inclusion ofdata/information), and downlink data/information is present inside theCOORD, the sequence of FIG. 10 may be modified wherein the COORD canoptionally send an additional frame with data/information aftertransmission of the first downlink frame, or following the reception ofan uplink frame. The first downlink frame may reserve the WM for theentire duration of the frame exchange, or at least for a portion of theframe exchange to allow a protected transmission of the uplink frame bya PER device, and without requiring a contention for the WM by the PERdevice. Optionally, the PER can acknowledge error free reception of thatframe.

Variations are possible, but in any case, the poll frame reserves themedium for subsequent frames such that frame exchange can happen with asingle medium contention; and frames transmitted by PER are protected bymedium reservation by COORD. For example, the COORD might send adownlink frame to PER1, send a downlink frame to PER2, and receive anuplink frame, all within one medium reservation.

An alternative frame exchange sequence is illustrated in FIG. 11. Themethod disclosed in FIG. 11 avoids situations where another STA accessesthe WM right before the scheduled data exchange between COORD and PER.This method can be used to minimize the power dissipation in the PER andimprove the Quality-of-Service (QoS) of the COORD-to-PER communicationlink. To prevent other STAs from accessing the WM in a time periodTreserve prior to the start of the scheduled data exchange, the COORD isawake prior to T0 and transmits a frame (frame 0), hereafter referred toas a “reservation frame” to reserve the WM.

At time TC0, a time Treserve prior to T0, the COORD gains access to theWM, either through contention or through a different medium accessmechanism, and transmits a first frame (frame 0), herein referred to asthe “reservation frame”. The frame arrangement of the reservation frameis such that the WM is reserved for a length of time equal or largerthan (Treserve−Taccess), where Taccess is the time needed to gain accessto the WM. In this way, no other STAs can transmit during the timebetween frame 0 has been transmitted and the start of the scheduled dataexchange, T0. As an example, if the reservation frame is an 802.11xframe or a modification thereof, the duration field in the header of thereservation field may be increased to reserve the WM for at least thelength of time specified above. At time T0, the COORD immediately sendsits first frame (frame 1) without having to gain access to the WM again.The further frame exchange can be the same as that of FIG. 10. The abovedescribed method minimizes the awake time for the PER, and improves QoS,at the cost of somewhat longer WM occupancy. Variations are alsopossible. As an example, in a slightly different embodiment, thereservation frame might reserve the WM for a longer length of time,thereby possibly eliminating the need for the downlink frame to reservethe WM.

If at time T0, the COORD has not gained access to the WM or has not yettransmitted frame 0, the COORD may decide to fall back to the frameexchange sequence described in FIG. 10. In such embodiment, the COORDcontinues to gain access to the WM (e.g., through contention) after timeT0. Once the COORD has successfully gained access to the WM, it mightdecide to skip the transmission of the reservation frame, frame 0, anddirectly transmit the downlink frame, frame 1.

In the frame exchange sequences described above, the COORD reserves theWM for the PER to avoid interference between a PWN and SWN. If thetransmission power of the secondary network is sufficiently low, a WMreservation mechanism may not be necessary. In such embodiments, a PERcan wake up and can directly access the WM, without waiting for a signalfrom the COORD. Optionally, a PER may wake up, detect whether the WM isidle and if not, contend for the WM prior to initiating a transmission.As an example, upon detection of a non-idle WM, the PER can follow arandom back-off procedure before attempting to access the WM.Alternatively, for power conservation reasons, upon detection of anon-idle WM, a PER may power down at least part of its circuitry andwake up a time later to try to access the WM again. A PER could go backto sleep for a pseudo-random period, which would result in theequivalent of a semi-random back-off, but while conserving power insidethe PER.

Optionally, a PER may rely on RSSI circuitry (an only wake up circuitrynecessary for RSSI) to detect whether the WM is idle and only wake upthe necessary circuitry for transmission after the WM has been detectedto be idle. If the transmission power of the PER is sufficiently low,communication in the secondary network will not cause any significantinterference to simultaneous traffic in the primary network. However,traffic in the primary network can cause transmission failures in thesecondary network. If this happens, a retry mechanism can be initiated,at the expense of some additional power usage.

Other variations of frame sequences are also possible. As an example, incase the HCCA mechanism is used to reserve the WM, the frame exchangebetween the COORD and PER may be preceded by a poll frame transmitted bythe AP of the dual-net device to grant a PWN TXOP to the dual-net deviceand the SWN traffic (downlink, uplink, etc.) that fits can be send usingthe TXOP provided by the AP.

Coordination of Multiple PERs

When a SWN includes multiple PERs as illustrated in FIG. 1 and describedherein, communication with such devices can be scheduled independently.However, in specific implementations, it may be desirable for a COORD tocoordinate the communication with multiple PERs that are part of thesame SWN in order to minimize the power dissipation, as well as topossibly reduce the WM occupancy. A method to coordinate thecommunication between a COORD and multiple PERs is shown in FIG. 12, andis an extension of the scheme of FIG. 10 to account for communicationwith more than one PER during a single SP.

At time T0, the COORD and PERs of a SWN (wireless PAN) are programmed tostart the frame exchange. If power-save modes are implemented in theCOORD or the PERs, a wake-up request will be issued prior to T0, toensure that all necessary circuits are powered up at time T0. At timeT0, the COORD tries to gain access to the WM and, optionally using thehighest priority queue (AC_VO) transmits a first frame (frame 1), thedownlink frame. Note that different mechanisms to access the WM may alsobe used. The frame format of the downlink frame is such that it reservesthe WM for the subsequent frame transmission possibly by more than onePER in its SWN. As an example, if the downlink frame is an 802.11x frameor a modification thereof, the duration field in its header might beincreased to reserve the WM for subsequent frame transmissions by one ormultiple PERs that are part of the COORD's SWN. The duration field ofthis frame might for example be increased to reserve the WM forsubsequent frame transmission by all PERs of the SWN that are scheduledfor a frame exchange during that specific SP.

Furthermore, the downlink frame contains a list of PERs it expects torespond, as well as an offset for each scheduled PER. As an example,this information can be included in a Traffic Indication Map (TIM) thatis part of the downlink frame arrangement, but other implementations arealso possible At the specified offset, each PER is awake and respondswith a frame, an uplink frame, containing its data (frame 2P1 and frame2P2). Optionally, the COORD acknowledges error free reception of theframe, or the COORD can respond with a frame that includes data to betransmitted from the COORD to the frame. Optionally, the PERacknowledges error free reception of the latter frame. Optionally, PERscan return to sleep during the time slots where the COORD iscommunicating with other PERs.

Modified versions of the scheme of FIG. 12 can be used to compensate forpacket loss and unsuccessful transmissions. As an example, if one ormore of the transmissions were not successful, the COORD may send anadditional frame immediately following the above described framesequence to reserve the WM for additional time to allow forretransmissions. This frame contains the PERs for which retransmissionis desirable as well as the corresponding offsets for each PER. PERsthat received acknowledgment of their transmission do not have to wakeup to listen to this additional frame. In one embodiment, it may be leftup to a PER to decide whether it will consider retransmission.

If the PWN is an 802.11(n) network, a Power Save Multi Poll (“PSMP”)frame or a modification thereof may be used as the downlink frame, butother frame formats are also possible.

An alternative frame exchange sequence for the coordination of multiplePERs is illustrated in FIG. 13. In this embodiment, the COORD polls eachPER individually. At the start of a Service Period (“SP”), the COORDaccesses the medium using regular medium access procedures (e.g.,contention) and after gaining access to the WM, the COORD polls the PERsin its SWN one by one with 1 SIFS space intervals. This is possible ifthe first downlink frame (“Frame 1”) reserves the WM for the subsequentframe sequence. The latter avoids the situation where the COORD has tocontend for the WM for each PER in its secondary network.

To conserve power in the PERs, the expected time for communication witheach PER can be pre-calculated based on the number of PERs that arescheduled to be polled prior to the respective PER and their scheduledtraffic size.

In case a transmission fails, a retransmission mechanism can beinitiated. Alternatively, the COORD may poll the next PER and come backto the failed transmission later, after it has polled all other PERs forwhich a communication event is scheduled during that specific SP.

Frame Formats

Different frame formats and frame types might be used for the downlinkand uplink frames. Depending on requirements, the frame formats/typesmight be those used elsewhere. For example, if the PWN is an 802.11xWLAN network and the SWN uses an overlay protocol that is an overlaywith respect to the 802.11x WLAN protocol, the frame formats/types mightbe of a form that a PWN device does not entirely understand, butunderstands enough to defer for a period to allow for SWN communication.

In one embodiment, the first frame transmitted by the COORD (thedownlink frame) is an 802.11x Clear-to-Send (“CTS”) frame with increasedduration field, and can be self-addressed or addressed to the PER.

In another embodiment, the downlink frame can be an 802.11x HCCA-CFframe of type data addressed to the PER and with the duration fieldincreased, with the subtype field “data” cleared and the subtype field“poll” set. In yet another embodiment, this frame can be an 802.11x HCCAdata frame addressed to the PER and with increased duration field, withthe subtype fields “data” and “poll” both set, and with thedata/information intended for the PER (that is downlinkdata/information) included in the payload. Other variations of HCCAframes might also be possible.

Typically, HCCA frames are only used for communication within a PWN(WLAN) to handle, for example, allocation of transmission opportunities.HCCA frames are used for communication between an AP and a STA of a PWNwhere the STA has set up a TS with the AP of the PWN. In that case, anHCCA-CF data frame of subtype “poll” might be transmitted by an AP usingan access scheme that is prioritized over the access schemes used bynon-AP STAs. A novel use of HCCA frame formats and arrangements isdisclosed in this invention, where HCCA frame formats and modificationsthereof and/or novel WM access schemes are used for communication withPERs in an SWN. Modifications may include but are not limited to the useof specific SWN-related information like the SWN's BSSID or the use ofthe “to DS” and “from DS” fields in the HCCA frame header (e.g., “To DS”and “From DS” both set to 0) to distinguish SWN (WPAN) traffic fromregular PWN (WLAN) HCCA traffic. Indeed, PWN (WLAN) HCCA frames arealways directed to or from an AP, resulting in either the “To DS” or“From DS” fields to be set to 1.

In addition, this invention describes a novel use of HCCA frames, inthat such frames are transmitted by a non-AP STA following non-AP mediumaccess schemes. As an example, in a specific embodiment, an HCCA-CF dataframe of subtype “poll” may be transmitted by a non-AP STA using basicnon-AP access schemes or possibly using the non-AP STA's priority queues(for example, the HCCA frame may be transmitted over the highestpriority queue for Voice traffic (AC_VO)). Moreover, the wireless mediumis reserved without colliding with an AP that may be using regularHCCA-CF frames of subtype “poll”, as might be the case if there was a 1PIFS delay before accessing the WM. HCCA-CF frames are used by accesspoints to ask a STA for a response to the HCCA, but they are used inthis example in a different way, for a different purpose.

In a specific embodiment, a dual-net device may decide to use some ofthe services from its PWN to schedule communication with PER devices inits SWN. As an example, if the dual-net device's PWN is an 802.11x WLAN,it may set up an 802.11 Traffic Stream (“TS”) with one or more PERdevices and use 802.11 mechanisms such as TSPEC and TCLAS (ormodifications thereof) to communicate the length of SIs, the start of anSP and the like with its PER devices. Unlike a conventional 802.11network, where such communication and negotiation occurs with an AP,when used for communication within a wireless PAN, specificcommunication with the AP of the PWN may be suppressed. As an example,the dual-net device may suppress the transmission of elements like“ADDTS” and “DELTS” to the AP it is associated with on its PWN.

In such an embodiment, a PER may initiate the creation of a TrafficStream (TS) to request the COORD for TXOPs, both for its owntransmissions as well as for transmissions from the COORD to itself. Ina specific implementation of this embodiment, a PER sends an Add TrafficStream (ADDTS) request frame to the COORD. The ADDTS request frames mayuse Traffic Specification (TSPEC) and optionally Traffic Classification(TCLAS) elements in its frame body containing the set of parameters thatdefine the characteristics and QoS expectations of the TS. The ServiceStart Time, Minimum Service Interval and Maximum Service Interval fieldsin the TSPEC element may be used to request a desired service period(SP) or update period as well as service time or update time. Inresponse to an ADDTS request frame, the COORD may send an ADDTS responseframe. This ADDTS response frame may use the TSPEC, TCLAS and scheduleelement in its frame body to exchange relevant parameters and announcethe schedule that the COORD will follow for traffic with the PER in thefuture. Following a successful negotiation, a TS is created. Once a TShas been created, the COORD polls the PER at the pre-negotiated servicestart time and with the pre-negotiated service intervals. For this,HCCA-CF poll frames, possibly with an identifier to indicate secondarynetwork communication, may be used. And HCCA-CF data frames may be usedto respond.

Different 802.11x frame formats, frame types, frame subtypes andmodifications thereof may also be used. As an example, management framesor data frames might be used. Specific fields in such frames may beadapted to indicate that the frames are part of a SWN overlay protocol.In some embodiments, regular frames are used, with their BSSID set tothe PAN's BSSID. Alternatively, HCCA frames or similar are used.

Direct Link Protocol

When the PWN is a WLAN network based on the 802.11x WLAN protocol, amechanism specified in the 802.11e specification, called Direct LinkProtocol or “DLP” may be re-used in a novel way to implement orfacilitate the communication in the SWN.

In one embodiment, the peripheral service function initiates a DirectLink Set-up (“DLS”). DLS is being specified in the 802.11e specificationas a protocol that allows two non-AP STAs in the same wireless LAN BSSto exchange frames directly without relying on the AP for the deliveryof the frames, and without having to disassociate from the wireless LANnetwork. FIG. 14 illustrates the steps involved in a regular direct link(“DL”) handshake. A station STA1 that intends to exchange framesdirectly with another non-AP station STA2, invokes DLS by sending a DLSrequest frame, frame 1, to the AP. Among other parameters, this requestcontains the MAC address of STA1 (source) and STA2 (destination). IfSTA2 is associated in the BSS, the AP can forward the DLS request toSTA2, frame 2. If STA2 accepts the direct stream, it sends a DLSresponse frame, frame 3, to the AP, which among other parameterscontains the MAC addresses of STA1 and STA2. The AP forwards the DLSresponse to STA1, frame 4, after which the DL becomes active and framescan be sent from STA1 to STA2 and from STA2 to STA1 without relying onthe AP.

According to the 802.11e specification, a Direct Link Set-up can only berequested for any two STAs that are associated with the same BSS. Thisis not directly applicable to communication between a COORD and a PER,since a PER is not associated with the primary network BSS. Therefore, astandard DLS cannot be used. Below, two novel methods are presented thatallow the use of DLS between two STAs, only one of which is associatedwith a wireless LAN BSS. Both methods are described in more detailbelow. The STA that is associated with the wireless LAN BSS is referredto as the COORD, whereas the other STA is referred to as the PER.

A first method is illustrated in FIG. 15. In this method, the COORDsends a DLS request frame to the AP of the primary network, frame 1,requesting a self-addressed Direct Link (DL). This can be achieved bysetting both the source and destination MAC address in the body of theDLS request frame equal to the COORD's MAC address. The DLS timeoutvalue can be set to zero such that the DL is never terminated based on atimeout. Alternatively, the DLS timeout value can be set to a valuecorresponding to a time period at the expiration of which it isdesirable that the DL be terminated. In response to a DLS request frame,the AP forwards the request, frame 2, in this case back to the COORD.The COORD accepts the direct stream and sends a DLS response frame tothe AP, frame 3. The AP forwards this response to the STA specified bythe MAC address in the DLS response frame, in this case back to theCOORD, frame 4. At the end of DLS handshake, the COORD can communicatedirectly with a PER in the secondary network without disassociating fromthe primary network by using secondary network frames. A secondarynetwork frame is the same or similar to a regular primary network framebut both the source address (SA) and destination address (DA) are setequal to the COORD's MAC address. In such frames the MAC address of thePER is included in a different field. In one embodiment, the MAC addressof the PER can be part of the frame body field.

In an alternative method, the COORD uses an indirect association andauthentication procedure to set up an authentication and association forthe PER with the AP. Once the PER has been associated and authenticated(indirectly) with the AP, the COORD may initiate a DLS with the AP bysending a DLS request frame with the source MAC address set to theCOORD's MAC address and the destination MAC address set to the PER's MACaddress. During the DLS procedure, the COORD responds to all frames sentby the AP of its primary network, including frames that are addressed tothe PER.

Connectivity States

The overlay protocol described herein might support multipleconnectivity states to meet typical wireless PAN needs, such as powerconservation, low latency requirements or the desire to minimize thenetwork capacity taken up by a single PER device. The latter isparticularly important if a large number of PER devices are operatingwithin a common wireless networking space, possible coexisting with alarge number of WLAN STAs sharing the same common wireless networkingmedium.

A possible state diagram illustrating connectivity states for a wirelessPAN device is illustrated in FIG. 16. It should be understood that thisis one example of a state diagram and devices might implement otherstate diagrams instead. Thus, this detailed example is for illustrativepurposes only. For example, a different state diagram might beapplicable if a single COORD coordinates multiple PER devices.

“Connected”

When in the CONNECTED state, the COORD and PER have agreed uponinactivity times, and communicate at agreed upon time intervals toexchange frames using frame formats, arrangements and sequencesdescribed herein. In addition, each is aware of the other, i.e., theyknow relevant addresses, etc., from prior communication that occurredduring prior states (as described below). Before entering the CONNECTEDstate, a COORD and PER might first go through a PAIRING, anUNCONNECTED-SCAN and a CONNECTION state.

To conserve power, the connected state might support different activitylevels. As an example, the Service Interval may be increased when nodata were sent for a specific length of time.

“Pairing”

The first step in establishing a new connection is device PAIRING.Device pairing comprises the first time configuration steps for linkinga PER to a COORD. The pairing procedure typically comprises at least twosteps: device discovery and a security pre-shared key exchange.

Device Discovery

During the device discovery procedure, MAC address information isexchanged between the COORD and the PER. A dedicated configurationpushbutton or a simple user action can be used to initiate devicediscovery. Other mechanisms are also possible, and several mechanismshave been documented in the literature. The exact mechanism to initiatedevice discovery is beyond the scope of this invention. Upon such userintervention, the COORD and PER might both enter a “limited discoverablemode” for a certain period of time that is long enough to finish thedevice discovery procedure. Both COORD and PER can initiate thediscovery procedure. The device that initiates the discovery procedureis called the “initiator”; the other device is hereafter referred to asthe “follower”.

Upon entering discoverable mode, the initiator sends a broadcastdiscovery request. The broadcast discovery request is a broadcast frame,and may contain information such as the initiator's MAC address, and thetype of devices that should respond. A follower in discoverable moderesponds to a broadcast discovery request with a discovery response. Thediscovery response frame is a unicast frame that is addressed to theinitiator.

For security reasons, it is advisable that the amount of informationexchanged while in discoverable mode is minimized. However, ifappropriate, additional information can be exchanged during the devicediscovery procedure. For example, if generated by the COORD, thebroadcast discovery frame may optionally contain information on the WLANconnectivity status (infrastructure/ad-hoc/unconnected, operatingchannel, power-save, etc.). If generated by the PER, the broadcastdiscovery frame may optionally contain information about the type ofPER.

In one embodiment, the COORD acts as the initiator and sends an 802.11xprobe request frame. The SSID parameter of the broadcast probe requestframe may be used to communicate specific information to the PER, inthis case the follower. More specifically, the SSID field in the framebody can be used as a frame type identifier and to send additionalinformation to a follower. For example, specific bits of the SSID can beused to identify the over-the-air protocol. Other bits of the SSID canbe reserved to identify the frame as a broadcast discovery requestframe. The remainder of the bits can be reserved or used to communicateadditional information about the COORD or the wireless LAN network it isassociated with to the PER (follower).

In another embodiment, a data frame or standard or proprietary IBSSbeacon frame or other management frame is used as a broadcast discoveryrequest frame.

Upon receiving the broadcast device discovery request frame, the PER indiscoverable mode (the follower) responds by sending a unicast discoveryresponse frame. This can be a unicast 802.11x probe response frame. Theprobe response frame is addressed to the initiator, and structured suchthat it is recognized as a discovery response frame by the initiator.Alternatively, the discovery response frame can be a data frameformatted to be recognized by the COORD as a discovery response frame.

A device discovery channel can be pre-defined in the protocol. In thatcase, an initiator put into discoverable mode will, by default, startsending broadcast discovery requests on the pre-defined channel, and afollower put in discoverable mode will, by default, listen for abroadcast discovery request on the pre-defined channel.

When device discovery is initiated, and no device discovery channel ispre-defined, the initiator and follower may need to search for eachother. Either the initiator or the follower may perform this search. Ifthe initiator performs the search, the follower listens on a fixedchannel, while the initiator scans different channels, by subsequentlytransmitting broadcast discovery request frames on different channels.Alternatively, when the follower performs the search, the initiatortransmits broadcast discovery request frames on a fixed channel atTdiscovery time intervals, while the follower performs a passive scan bylistening for a broadcast discovery request on different channels. Notethat the follower should stay on a single channel for at leastTdiscovery to ensure it will capture a broadcast discovery frame.

At the conclusion of the device discovery procedure, at a minimum, theinitiator and follower have knowledge of each other's MAC address andcurrent operating channel of the COORD's primary network.

Security Key Exchange

Initial key set-up and key management constitutes an important aspect ofsecure wireless communication. The IEEE 802.11 standard specifies thatthe secret shared key be delivered to participating stations via asecure channel that is independent of IEEE 802.11. This is notnecessarily possible when attaching a power-sensitive device like a PER.Over-the-air transmissions may be required to distribute a pre-sharedencryption key between participating stations.

Preferably, not the key itself, but the minimum required key informationfrom which the secret shared key can be derived by both sides of thelink is transmitted over-the-air.

After completing the device discovery procedure, the COORD and PERexchange the necessary information to acquire common knowledge of ashared secret key. This process is referred to as the key setup, and theshared secret key exchanged in this phase is called the pre-shared key.Several actions may be taken to minimize chances of a pre-shared keyinterception. Such actions may include, but are not limited to, (1)sending critical information from PER to COORD, (2) intentionallyreducing power levels for pre-shared key information exchanges, and/or(3) using a key exchange process, such as Diffie-Hellman, to avoidhaving critical key information transmitted over the air in the clear.Sending critical information from PER to COORD reduces the chances ofinterception, since the transmission range of a PER might besignificantly lower that that of a COORD.

The pre-shared key is stored and can be used for encryption of frames bythe driver or firmware that performs the encryption of frames forcommunication in the secondary network. For security reasons, it isoften desirable to regularly update the shared key. The pre-shared keycan be used to encrypt one or more temporary keys before they aretransmitted over the air. These temporary keys are then used forencryption and authentication of data.

The COORD may initiate the initial key exchange, and may reserve the WMby increasing the duration field of the frame it sends to a PER. Duringthe initial key exchange, frames sent to a PER should not be encrypted.If the COORD is a dual-net device, this can be achieved by eitherturning off encryption in the COORD's 802.11x device driver or firmwareor passing the frame on to the 802.11x device driver beyond theencryption point. Similarly, frames received from the PER during theinitial key exchange should not be decrypted by the 802.11 device driveror firmware. This is achieved either by turning off encryption in theCOORD's 802.11x device driver or firmware, or by making sure that thereceived frame is passed on to the peripheral service function prior todecryption in the 802.11x device driver or firmware. Furthermore, thedata rate of frame transmissions is set to the maximum data ratesupported by the PER.

Completion of Pairing Procedure

After successful completion of the pairing procedure, the MAC address ofthe COORD and the shared key information are stored inside the PER, andthe MAC address of the PER and the shared key information are storedinside the COORD. Both the COORD and PER abandon the limiteddiscoverable mode. The COORD and PER are now paired. After completion ofthe pairing procedure, the COORD continues its regular WLAN activity.

The PER may subsequently decide to go enter the DEEPSLEEP state or enterthe UNCONNECTED-SCAN state.

BSS Notification

In case where the COORD, STA1, is associated with a primary networkBSS1, prior to starting the pairing procedure, it may be desirable tonotify the AP of BSS1 that STA1 will be temporarily unavailable. Thismay be important to avoid the situation where BSS1 tries to communicatewith STA1 while STA1 is occupied with the pairing. The BSS1 traffic mayeven be on a different channel (such as where there is a pre-defineddiscovery channel). If non-responsive, the AP might drop STA1 fromassociation with the AP.

A first method may comprise temporarily disassociating the client fromthe primary network, BSS1. Since the pairing procedure is normally doneonly once, at initial set-up, it may in many applications be acceptablethat, for the duration of the pairing procedure, STA1 temporarilydisassociates from BSS1.

In a second method, STA1 may notify the AP of its primary network BSS1of its temporary unavailability by sending a frame with the powermanagement bit set. After completing the pairing procedure, STA1 maysend a frame to the AP of BSS1 with the power management bit cleared.

“Unconnected-Scan”

When in the UNCONNECTED-SCAN state, a PER device tries to detect theCOORD that it is paired with. Various scanning and device detectionschemes might be used when in the UNCONNECTED-SCAN state.

In one embodiment, the connection request frame is a probe request frameand can be generated with a scan request. The broadcast probe requestframe may have the SSID programmed to be interpreted by the PER as aconnection request frame. The SSID may, among other parameters, containthe PER's MAC address information, a secondary network protocolidentifier, and a connection request frame identifier. It mayfurthermore contain relevant additional parameters, such as the wirelessLAN connection mode (infrastructure versus ad-hoc versus no connect),the operating channel of the COORD's wireless LAN connection, etc. TheCOORD may also reserve the WM for a single response frame from the PER.The protocol states described herein (ACTIVE, PAIRING, etc.) mightcollectively define portions of a secondary network protocol.

In another embodiment, a data frame or a standard or proprietary IBSSbeacon frame may be used as a connection request frame. Alternativemanagement, control or data frames beyond the above specified examplesmay also be used as connection request frames.

As with the pairing procedure, the connection request frames are eithertransmitted on a pre-defined channel, or a COORD- or PER-initiatedsearch may be used to establish connection.

“Connection”

A connection procedure can be initiated at any time between a PER and aCOORD that are paired, have detected each other, but are not yetconnected. The purpose of the connection procedure is to prepare theCOORD and PER for regular frame exchange (“ACTIVE state”). During theconnection procedure, the PER and COORD are synchronized and,optionally, a new shared encryption key is exchanged.

Authentication

Optionally, an authentication procedure may be added prior to dataexchange to ensure that the claimed recipient is indeed the intendedrecipient. A standard shared key authentication procedure, alreadysupported by the 802.11x stack, may be used for authentication.Alternatively, a new authentication mechanism may be implemented in the802.11x peripheral service function.

Update Shared Encryption Key

For security reasons, it may be desirable to regularly update theencryption key, so that even if the key is intercepted, the connectionis not insecure indefinitely. In one specific embodiment, the encryptionkey is temporary and may be updated every time a new connection isestablished. In such embodiment, the pre-shared key may be used toexchange information related to the shared encryption key.

Completion of Connection Procedure

Upon completion of the connection procedure, the COORD and the PER areready to exchange data/voice traffic, and both enter the CONNECTEDstate. At that point, the PER has knowledge of the operating channel andother relevant parameters related to the COORD's primary network.

Similar as during the pairing procedure, it may be desirable that theCOORD notifies the AP of its primary network that it will temporarily beunavailable. This can among other mechanisms be done by sending a frameto the AP with the power management bit set. After completion of theconnection procedure, COORD may send a frame to the AP with the powermanagement bit cleared.

“Deepsleep”

If there has been no traffic for a time longer than a pre-defined timeinterval Ttime_out, the PER may enter the DEEPSLEEP state. In theDEEPSLEEP state, the PER powers down most or all of its circuits anddoes no longer stay synchronized to the COORD. When in the DEEPSLEEPstate, prior to go back to ACTIVE state, the PER first goes through theUNCONNECTED-SCAN and CONNECTION states.

Alternatively, the PER may enter the DEEPSLEEP state after a power-downevent, when failing to receive frames from the COORD or when receiving aPARK request from the COORD or from a higher level management layer.

When the PER has entered the DEEPSLEEP state, the COORD might determineto switch to the UNCONNECTED-SCAN state, where it periodically oroccasionally checks whether a PER is trying to connect. Optionally, allconnections might use a fixed, pre-defined channel for rendezvous.

Overlay Protocol with PWN Feature/Hardware Reuse

In specific embodiments, a computing device is a dual-net device and isinterfaced to a wireless local area network (WLAN) and a wirelesspersonal area network (PAN). A network circuit, comprising logic and atleast one antenna, interfaces the computing device to the WLAN andincluding logic to set up a LAN association between the computing deviceand the access point prior to data transfer therebetween, while alsointerfacing the computing device to a PAN device via the wireless PAN.

Communication with the wireless PAN device might use an SWN overlayprotocol that is only partially compliant with the protocol used over aconventional WLAN and might do so without interference from theconventional WLAN, yet usage of the WLAN is such that the wireless PANdevice and computing device can communicate without interference. Toreduce interference, the computing device coordinates the usage of thewireless medium with devices of a WLAN that may be active in the samespace. Coordination is achieved by the use of a secondary network (PAN)protocol that is an overlay protocol that is partially compatible withthe WLAN protocol, but not entirely, in terms of power, frame contentsand sequences, timing, etc. The secondary network (PAN) protocols mightbe 802.11x frames with new frame arrangements adapted for PAN needs,such as reduced latency, power etc. The computing device might determineto signal the primary network (WLAN) such that devices therein defer sothat communications can occur with the secondary network. The overlayprotocol is preferably such that devices that can join both networks canuse a common network interface circuit.

In specific implementations, a shareable network circuit storesparameters, addresses and other information necessary to maintainsessions with both networks simultaneously. As an example, a shareablenetwork circuit may store two media addresses, one for communication inthe WLAN and one for communication in the wireless PAN. The networkcircuit can maintain sessions with both simultaneously. More than twonetworks and corresponding storage of parameters, addresses andadditional network related information might be provided for. Arecognition method is provided in the computing device to distinguishand separate traffic from different networks.

Where the PWN is a WLAN typically used for network traffic over arelatively large space, such as a building and the SWN is a PAN istypically used for peripheral traffic over a narrower space, such as aroom, a desk, a person's space, etc., the optimum protocols for the twonetworks are likely to be different such that what works well for onenetwork does not work well for another network. Nevertheless, if asingle computing device is to be a part of both networks, it isdesirable to re-use specific PWN features and networking hardware forcommunication in the SWN. Where the first network is an 802.11x networkand a computing device includes 802.11x networking equipment, an overlayprotocol can be used for the SWN, such that 802.11x equipment can beco-opted for use with the SWN, optimized to deal with some of thediffering requirements of the two networks.

The overlay protocol allows a dual-net device that is associated with aPWN to exchange information, possibly on the same channel as the primarynetwork, with PERs that are a member of a SWN, and not a member of thePWN, and that may or may not be within the coverage range of the PWN.Access to specific lower level primitives in the 802.11x stack, like theability to overwrite a frame's duration field, or the ability totransmit/receive on a separate SWN BSSID may or may not be necessary.

As an example of PWN feature reuse, the SWN overlay protocol may usemodulations schemes supported by the PWN protocol, so as to enablere-use of the modulation/demodulation logic in the 802.11x equipment. Asanother example of PWN feature reuse, the SWN overlay protocol may use802.11x frame arrangements and modifications thereof, so as to ensurethat frames in the SWN can be transmitted and received by the 802.11xhardware.

In a specific implementation, for a dual-net device to maintain multiplesessions simultaneously, it stores two media addresses, one forcommunication with devices in the WLAN and one for communication withdevices in the wireless PAN. The media addresses can be network BasicService Set Identifiers (BSSIDs). The BSSID for the primary network canbe the MAC address of the AP of the primary network, and the BSSID forthe secondary network can be a MAC address that identifies WPAN traffic.As an example, the BSSID of a secondary network can be the WLAN MACaddress of the dual-net device, but it can also be a MAC address that isdifferent from the dual-net device's WLAN MAC address. As anotherexample, the BSSID of the secondary network may be global media addressto identify WPAN traffic, that is a single MAC address that uniquelyidentifies all wireless PAN traffic independent of what COORD thewireless PAN traffic is intended for.

In a different implementation of the protocol however, the BSSID of thePWN is re-used and a separate MAC address for the communication in theSWN is not needed.

More than two networks and corresponding storage of addresses andparameters might be provided for.

A dual-net device that is simultaneously maintaining a session with aWLAN and a wireless PAN can use a packet recognition mechanism todistinguish traffic in the PWN (the WLAN) from traffic in the SWN (thewireless PAN).

In a specific implementation where the wireless PAN BSSID is differentfrom the WLAN BSSID, a dual-net device can use the BSSID in the packetto distinguish traffic in the primary network from traffic in thesecondary network.

Other identification mechanisms, like an Ethertype, an organizationallyunique identifier (OUI), specific reserved bits in an 802.11x packetetc. may also be used to identify wireless PAN traffic.

In yet another implementation, the SWN protocol may be such that thedual-net device knows when a wireless PAN frame can be expected. Anexample of such protocol is a “polling-based” protocol where a PER onlysends a frame to its COORD in response to reception of a frame from itsCOORD. If the dual-net device knows when to expect a wireless PAN frame,it can prepare a temporary buffer for such frame. In the above example,each time the COORD transmits a frame that is intended for a PER, atemporary buffer for a single reply frame might be provided. Thisidentification method works if a PER does not access the WMautonomously, and responds to a frame for the COORD with a single replyframe. The method can easily be extended, using the teachings herein, tothe scenario where a PER responds to a frame from the COORD withmultiple reply frames by increasing the size of the temporary buffer.

In yet another embodiment, a modified 802.11x frame format is used forcommunication in the SWN. For example, HCCA data frames with “from DS”and “toDS” fields both cleared might automatically be recognized by the802.11x stack as wireless PAN traffic.

Alternatively, if no recognition mechanism is provided by the 802.11xstack, all received frames can be propagated up to the 802.11xperipheral service function, and a recognition mechanism implementedinside the 802.11x peripheral service function selects the frameoriginating from a PER.

In addition to a recognition mechanism to distinguish WLAN traffic fromwireless PAN traffic, an additional recognition method may be needed todistinguish traffic from separate wireless PANs. As an example, two ormore COORDs of separate wireless PANs may be sharing a common wirelessnetworking medium. If that is the case, a COORD may be receiving framesfrom devices that belong to different wireless PANs and should beconfigured to distinguish frames from its own wireless PAN from thosethat belong to a different wireless PAN. If a different media address isused for each wireless PAN (for example, each wireless PAN has a uniquewireless PAN BSSID), then identification can be done based on such mediaaddress.

In a specific implementation, a global unique media address may be usedto globally identify all wireless PAN traffic. As an example, a globalunique BSSID may be used to identify all wireless PAN traffic. In suchimplementations, an additional identification mechanism may be requiredto allow a COORD to identify the wireless PAN traffic for which it isthe intended recipient. As an example, the Destination Address (“DA”) orReceiver Address “RA”) field of the 802.11x packets can be used as suchidentifier. The DA or RA can, for example, be the WLAN MAC address ofthe COORD. Other similar approaches can be used instead.

Variations

In a common operation, a link is established between a network circuitand a BSS while simultaneously linked with a secondary network device.In one variation, some aspects could also be used to establish a linkbetween a standard 802.11x card and a power-sensitive device, even ifthe standard 802.11x card is not simultaneously connected to a BSS. Forexample, in a GSM/WiFi combo phone, the device might be handling a callover the cellular network and the WiFi card could still be used forheadset connectivity.

In the 802.11e draft, HCCA is proposed to be used by the QAP to scheduletraffic with QSTAs. In embodiments described herein, it is used forcommunication in secondary network. Thus, while COORD is regular clientin the primary network, difference can be signalled with specific fieldsin frame set differently (e.g., “to ds” and “from ds” both set tozeroes, or via the use of some of the reserved bits). An example isshown in FIG. 17.

Additionally, in order not to interfere with other “real” HCCA APs, adifferent access procedure can be used (e.g., use the VoIP queue insteadof PIFS). The HCCA mechanism can be reused for a service request (i.e.,a connection) using ADDTS request and response frames with TSPEC andschedule element, for HCCA CF polls (e.g., COORD polling the PER inCONNECTED state), and/or for schedule frame for changing update intervaleither because PER goes into SNIFF mode or in case of congestion of themedium to free up the WM and save power inside PER.

In many of the examples described herein, one feature is the use of acommon PHY and MAC layer for two networks, one being a conventional802.11x network with a BSSID and the other being a secondary networkconnecting what would otherwise be an 802.11x STA with peripherals andother low-power, low-range devices. In a more general case in anothernetwork model, there is common use of a modulation scheme and a frameformatting layer, wherein the PHY and MAC are specific instances.

In many of the examples described herein, the station device iswirelessly coupled to an 802.11x access point while being active withdevices over the secondary network. In other variations, the stationdevice is wirelessly coupled to another station over a direct link whilebeing active with devices over the secondary network. In yet othervariations, the station device may be the AP of the primary network,while also being the COORD for the secondary network.

In some embodiments, the communication between the COORD and one or morePERs of the SWN occurs in the same frequency band and on the samefrequency channel as the communication of the PWN.

In other embodiments, the communication between the COORD and one ormore PERs of the SWN occurs in the same frequency band as thecommunication in the PWN, but on a different frequency channel than thecommunication within the PWN. As an example, channel switching may bedesirable if the frequency channel of the PWN is crowded, or the SWNapplication requires a high Quality of Service (QoS).

In other embodiments, the communication between the COORD and one ormore PERs of the SWN occurs in a different frequency band and, thereforealso on a different frequency channel, as the communication of the PWN.As an example, frequency band switching is necessary if the primarynetwork is in an 802.11a mode, operating in the 5 GHz unlicensedfrequency band and the PER only supports communication in the 2.4 GHzunlicensed frequency band, or vice versa.

In still further embodiments, the dual-net device may be communicatingin a different mode with the PWN and the SWN. As an example, the COORDmay be communicating in an 802.11g mode inside the PWN while using an802.11b mode for communication within the SWN, or vice versa. In suchembodiment, the communication within the SWN can be on the same or on adifferent frequency channel as the PWN.

In yet another embodiment, communication in the SWN uses the same modeas the PWN, with both networks using different data rates or where it isnot known whether the data rates are different or the same (such aswhere they are set independently). For example, the COORD might transmitframes at the same data rate as its data rate for communication withinthe primary network while the PER communicates with the COORD using adifferent data rate.

Different data rates might be used for downlink and uplink communicationwithin the SWN. Alternatively, the same data rate is used for downlinkand uplink communication within the SWN and this data rate is differentfrom the data rate used by the dual-net device for communication withinthe PWN. It is also possible that the data rates for PWN and SWNcommunication are set independently, but at certain moments in time turnout to be the same.

In the typical embodiment in an 802.11x environment, an 802.11x clientcan talk to an access point and devices in the secondary network withoutlosing synchronization and association and without requiring a reset ofa connection at the 802.11x client. The 802.11x client can reserve awireless medium for a weak peripheral, effectively solving a “hiddennode” problem for the low-power peripheral or other such device.

In a common operation, a link is established between a network circuitand a BSS while simultaneously linked with a secondary network device.In one variation, some aspects could also be used to establish a linkbetween a standard 802.11x card and a power-sensitive device, even ifthe standard 802.11x card is not simultaneously connected to a BSS. Forexample, in a GSM/WiFi combo phone, the device might be handling a callover the cellular network and the WiFi card could still be used forheadset connectivity.

In many of the examples described herein, one feature is the use of acommon PHY and MAC layer for two networks, one being a conventional802.11x network with a BSSID and the other being a secondary networkconnecting what would otherwise be an 802.11x STA with peripherals andother low-power, short-range devices. In some embodiments, only part ofthe MAC layer is in common and other variations are possible. In a moregeneral case in another network model, there is common use of amodulation scheme and a frame formatting layer, wherein the PHY and MACare specific instances.

In many of the examples described herein, the station device iswirelessly coupled to an 802.11x access point while being active withdevices over the SWN. In other variations, the station device iswirelessly coupled to another station over a direct link while beingactive with devices over the SWN. In yet other variations, the stationdevice may be the AP of the PWN, while also being the COORD for the SWN.

In the typical embodiment in an 802.11x environment, an 802.11x STA cantalk to an access point and to devices in the SWN without losingsynchronization and association and without requiring a reset of aconnection at the 802.11x STA. The 802.11x STA can reserve a wirelessmedium for a weak peripheral, effectively solving a “hidden node”problem for the low-power peripheral or other such device.

In many of the examples herein, where a device is described as adual-net device it is intended to be a description of a device that canbe a coordinator for a SWN while being a station in a PWN. Often thedescription of operations, features and/or elements of the dual-netdevices also apply to secondary wireless PAN COORDs that may not have acapability to become a full node in the primary network.

Even where differences between the PWN and SWN are such that they don'tinterfere, the COORD might still reserve the WM, to avoid signals fromelsewhere interfering.

While the present invention has been described herein with reference toparticular embodiments thereof, a latitude of modification, variouschanges, and substitutions are intended in the present invention. Insome instances, features of the invention can be employed without acorresponding use of other features, without departing from the scope ofthe invention as set forth. Therefore, many modifications may be made toadapt a particular configuration or method disclosed, without departingfrom the essential scope and spirit of the present invention. It isintended that the invention not be limited to the particular embodimentsdisclosed, but that the invention will include all embodiments andequivalents falling within the scope of the claims.

What is claimed is:
 1. A method of communicating between devices of apersonal area network (PAN) using a wireless medium that is shared witha wireless local area network (WLAN), the method comprising: obtainingaccess to the wireless medium for a PAN coordinator device, whereinaccess to the wireless medium is allocated to the PAN coordinatordevice; signaling a reservation of the wireless medium by the PANcoordinator device, such that other WLAN devices receiving the signalingdefer use of the wireless medium for a reservation period, thereservation being signaled by the PAN coordinator device using one ormore frames of a PAN protocol that are at least partially understandableby the other WLAN devices, wherein the WLAN is an 802.1 lx network andthe one or more frames of the PAN protocol are 802.1 lx frames directedto a PAN device and include in a header of the frames, an increasedduration field; and communicating, using the PAN protocol, between thePAN coordinator device and a PAN device over the wireless medium duringthe reservation period.
 2. The method of claim 1, wherein the one ormore frames using the PAN protocol comprise a frame directed to a PANdevice having an increased duration field.
 3. The method of claim 2,wherein the one or more frames using the PAN protocol comprise an802.11x CTS frame with an increased duration field.
 4. The method ofclaim 2, wherein the one or more frames using the PAN protocol comprisean 802.11x frame or modification thereof, transmitted using a highestpriority queue.
 5. The method of claim 2, wherein the one or more framesusing the PAN protocol comprise an HCCA-CF poll frame having a pluralityof subtype fields including a “data” subtype field and a “poll” subtypefield, wherein the HCCA-CF poll frame is sent with its “data” subtypefield cleared and its “poll” subtype field set.
 6. The method of claim2, wherein the one or more frames using the PAN protocol comprise amodified HCCA-CF poll frame that is partially compliant with WLANprotocol, the modified HCCA-CF poll frame having a plurality of subtypefields including a “data” subtype field and a “poll” subtype field,wherein the HCCA-CF poll frame is sent with its “data” subtype fieldcleared and its “poll” subtype field set.
 7. The method of claim 2,wherein the one or more PAN protocol frames includes data addressed to aPAN device.
 8. The method of claim 2, wherein the one or more framesusing the PAN protocol comprise an HCCA-CF poll frame having a pluralityof subtype fields including a “to DS” subtype field and a “from DS”subtype field, wherein the HCCA-CF poll frame is sent with both subtypefields cleared.
 9. The method of claim 2, wherein the one or more PANprotocol frames are transmitted using a highest priority queue.
 10. Awireless network interface circuit for communicating between devices ofa personal area network (PAN) using a wireless medium that is sharedwith a wireless local area network (WLAN), the circuit comprising:circuitry for conveying signals between the wireless network interfacecircuit and a computing device to which the wireless network interfacecircuit is electrically coupled; logic for obtaining access to thewireless medium; logic for signaling a reservation of the wirelessmedium, such that other WLAN devices receiving the signaling defer useof the wireless medium for a reservation period, the reservation beingsignaled using one or more frames of a PAN protocol that are at leastpartially understandable by the other WLAN devices, wherein the WLAN isan 802.1 lx network and the one or more frames of the PAN protocol are802.1 lx frames directed to a PAN device and include in a header of theframes, an increased duration field; and logic for communicating, usingthe PAN protocol, with a PAN device over the wireless medium during thereservation period.
 11. The circuit of claim 10, wherein the one or moreframes using the PAN protocol comprise a frame directed to a PAN devicehaving an increased duration field.
 12. The circuit of claim 10, whereinthe one or more frames using the PAN protocol comprise an 802.11x CTSframe with an increased duration field.
 13. The circuit of claim 10,wherein the one or more frames using the PAN protocol comprise an802.11x frame or modification thereof, transmitted using a highestpriority queue.
 14. The circuit of claim 10, wherein the one or moreframes using the PAN protocol comprise an HCCA-CF poll frame having aplurality of subtype fields including a “data” subtype field and a“poll” subtype field, wherein the HCCA-CF poll frame is sent with its“data” subtype field cleared and its “poll” subtype field set.
 15. Thecircuit of claim 10, wherein the one or more frames using the PANprotocol comprise a modified HCCA-CF poll frame that is partiallycompliant with the WLAN protocol, the modified HCCA-CF poll frame havinga plurality of subtype fields including a “data” subtype field and a“poll” subtype field, and wherein the HCCA-CF poll frame is sent withits “data” subtype field cleared and its “poll” subtype field set. 16.The circuit of claim 10, wherein the PAN protocol frame includes dataaddressed to a PAN device.
 17. The circuit of claim 10, wherein the oneor more frames using the PAN protocol comprise an HCCA-CF poll framehaving a plurality of subtype fields including a “to DS” subtype fieldand a “from DS” subtype field, wherein the HCCA-CF poll frame is sentwith both subtype fields cleared.
 18. The circuit of claim 10, whereinthe one or more PAN protocol frames are transmitted using a highestpriority queue.